“LED lamp” in the following is to be understood as a lighting appliance which with the aid of standard fittings (E12, E14, E26, E27, GU10 . . . ) can be used directly for example in order to replace incandescent lamps (also referred to as “retrofit”). The external shape and the appearance are for the most part modeled on incandescent lamps and meet the standards, for example with regard to the external dimensions.
Dissipation of the heat generated at the LEDs is absolutely essential for LED lamps. For the most part, passive cooling (without a fan) is called for, whereby passive cooling members are however comparatively bulky. With regard to so-called “retrofit” LED lamps which emulate conventional lamps, in particular incandescent lamps, and can be inserted in the standard fittings (E12, E14, E26, E27, GU10 etc.) thereof, the passive cooling members should moreover emulate the external shape of incandescent lamps. From this results a rotational symmetry which has hitherto been designed using one-piece cooling members, for the most part made of aluminum or an aluminum alloy. The problem is that for reasons of space an electronic driver circuit needs to be incorporated into a mounting cavity in the interior of the cooling member for operation of the LED lamp or of the LED(s). The opening is typically open at the lower end (in the region of the lamp cap) and closed at the mounting surface of the LED(s) in order that the LED(s) can be connected to the cooling member without any air gaps as far as possible in order to avoid thermal bottlenecks. However, the shaping of this hollow space has hitherto been restricted to straight edges during manufacture of the cooling member; in particular it is not possible to emulate an incandescent lamp shape in the interior, which results in increased consumption of materials due to a solid construction. It has also hitherto been necessary to laboriously route cables from the electronic driver circuit to the LED(s) through small holes, which makes for a high manufacturing resource requirement.
EP 1 047 903 B1 discloses an LED lamp having a column, a lamp cap which is connected to an end of the column, and a substrate which is connected to the other end of the column and which is provided with a number of LEDs, whereby the substrate has a regular polyhedron having at least four faces, whereby faces of the polyhedron are provided with at least one LED which, during operation of the lamp, has a luminous flux of at least 5 lm, and whereby the column is provided with heat-dissipating means which interconnect the substrate and the lamp cap.
EP 1 503 139 A2 discloses a compact LED light source which provides LED positioning along with thermal dissipation. The LED light source can be made with a heat-conductive plate which supports a plurality of LEDs mounted on the plate and in thermal contact with the plate. The plate further supports electrical circuitry which provides an electrical connection to the LEDs. A heat-conductive stem mechanically supports the plate and may provide a thermal conduction path from the plate away from the LEDs. A high concentration of LEDs can then be conveniently mounted and held in close proximity for increased optical system intensity, while providing a thermal exit path for the associated increase in heat concentration.